The present invention relates to a rear projection screen and, more particularly, to a rear projection screen which has a sufficiently high screen gain, uniform luminance intensity, and uniform color balance at a wide angle of view.
Recently, a rear projection system or a light-transmitting projection system such as a projection television system, a projection screen display system or an enlarged projection system has been widely used. FIG. 1 shows a rear projection system having a rear projection screen 1 and a projecting apparatus 2. In the rear projection system of the type described above, an image signal is separated by a receiver 3 into color signals of red, green and blue. These color signals are supplied to cathode ray tubes 4R, 4G and 4B, respectively. Red, green and blue color images from cathode ray tubes 4R, 4G and 4B respectively are projected onto the rear projection screen 1 through projection lenses 5R, 5G and 5B respectively. The color images are synthesized into a composite picture image, thereby allowing the user to observe the picture image on the rear projection screen 1.
A so-called "a lenticular-lens plate or a lenticulated plate" which has one flat surface and one surface constituted by a number of elongated columnar lenses aligned with each other is known as the rear projection screen 1 to be applied to the rear projection system described above. In addition to the lenticular-lens plate, a Fresnel lens, a diffusing plate, or a combination thereof, is also known as a rear projection screen. However, when these screens are used in the transmitting type of projection system, the cathode ray tubes 4R, 4G and 4B are disposed adjacent to each other and cannot be located in the same position. The optical axes of the projection lenses 5R, 5G and 5B respectively corresponding to the cathode ray tubes 4R, 4G and 4B cannot coincide with each other. As a result, these optical axes cross each other at slightly different angles with respect to the rear projection screen 1, as shown in FIG. 1. The angles of incidence of light rays transmitted from the cathode ray tubes 4R, 4G and 4B to corresponding regions on the rear projection screen 1 differ from each other since a distribution of light on the screen depends on the incidence angle of light rays, color components transmitted onto the screen 1 differ in the respective viewing direction. As a result, uniform luminance distribution cannot be obtained, or luminance of the overall picture image is degraded.